Open AccessCrosshole seismic waveform tomography – II. Resolution analysis
Author(s) -
Rao Ying,
Wang Yanghua,
Morgan Joanna V.
Publication year - 2006
Publication title -
geophysical journal international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.302
H-Index - 168
eISSN - 1365-246X
pISSN - 0956-540X
DOI - 10.1111/j.1365-246x.2006.03031.x
Subject(s) - smoothing , geology , inversion (geology) , waveform , tomography , inverse theory , grid , seismic tomography , borehole , perturbation (astronomy) , seismic velocity , geodesy , seismology , algorithm , geophysics , computer science , mathematics , tectonics , optics , statistics , physics , geotechnical engineering , telecommunications , radar , deformation (meteorology) , oceanography , quantum mechanics , mantle (geology)
SUMMARY In an accompanying paper, we used waveform tomography to obtain a velocity model between two boreholes from a real crosshole seismic experiment. As for all inversions of geophysical data, it is important to make an assessment of the final model, to determine which parts of the model are well‐resolved and can confidently be used for geological interpretation. In this paper we use checkerboard tests to provide a quantitative estimate of the performance of the inversion and the reliability of the final velocity model. We use the output from the checkerboard tests to determine resolvability across the velocity model. Such tests can act as good guides for designing appropriate inversion strategies. Here we discovered that, by including both reference‐model and smoothing constraints in initial inversions, and then relaxing the smoothing constraint for later inversions, an optimum velocity image was obtained. Additionally, we noticed that the performance of the inversion was dependent on a relationship between velocity perturbation and checkerboard grid‐size: larger velocity perturbations were better‐resolved when the grid‐size was also increased. Our results suggest that model assessment is an essential step prior to interpreting features in waveform tomographic images.